1. Field of the Invention
The present invention relates to a device for sensing the position of a motor vehicle relative to a trailer or other draft vehicle. The device includes a visual display representing the relative positions of the vehicles. The purpose of this invention is to assist in backing up a towing vehicle to a draft vehicle by providing a visual display proximate the operator.
2. Description of the Prior Art
Backing up a vehicle to another vehicle for the purpose of connecting the two vehicles, as for towing, is a difficult undertaking. The connection apparatus, which generally comprises an upwardly projecting ball fastened to the towing or tow vehicle, and a cooperating socket fastened to the draft or towed vehicle, are generally quite small, compared to the dimensions of the respective vehicles.
Maneuvering one vehicle into alignment with the second so that the aforementioned connection apparatus is properly aligned, and within close proximity so that the ball and socket can mate, is difficult. This is because mostly, vehicles are driven forward, whereas the present maneuver is conducted while backing up. Chassis behavior is considerably different when reversing the position of the steering road wheels, relative to the direction of motion. Most drivers are not highly experienced in dealing with reverse operation.
Compounding the above problem is that visibility to the rear is inadequate in most vehicles. This is especially true when considering that most balls and sockets are mounted at bumper level, which is generally low on the respective vehicle bodies. Thus, there is rarely a direct line of sight between the driver and either the ball or the socket. It is therefore virtually guesswork to estimate the relative positions of these components. An alternative would be to have a second person stand outside the vehicle, observe the relative positions, and give verbal instructions to the driver.
While an assistant would ameliorate the driver's task, there remains considerable room for improvement. Two ways of improving the driver's view of the relative positions of the vehicles is proposed in the prior art. U.S. Pat. No. 5,269,554, issued to Benjamin J. Law et al. on Dec. 14, 1993, discloses a direct visual aid for aligning two vehicles. The towing vehicle and the draft vehicle each have a telescoping indicator for direct viewing and aligning.
U.S. Pat. No. 5,180,182, issued to James R. Haworth on Jan. 19, 1993, discloses a mirror arranged to deflect a vehicle operator's line of sight advantageously around the tailgate of a pickup truck, so that he or she can observe alignment of the pickup truck with a draft vehicle.
Improvements upon the above schemes are seen in some arrangements wherein it is proposed to sense the relative positions automatically, and to provide the driver with instructions or other annunciation of the determined positions.
U.S. Pat. No. 3,825,921, issued to Louis J. Marus et al. on Jul. 23, 1974, and U.S. Pat. No. 3,924,257, issued to Jack E. Roberts on Dec. 2, 1975, are of some relevance to the present invention. These approaches employ an emitting coil and an induction coil. When out of axial alignment, parallel to vehicle axes, a control circuit generates a proportional signal.
Roberts provides two indicators for indicating, respectively, the direction and magnitude of misalignment. The indicators are of the visual type, such as needle gauges, preferably located in close proximity to one another in the cab of the vehicle. Thus, both indicators are within easy visual access of the driver. Marus et al. provides a single indicator in the form of a needle gauge.
Other automated schemes providing primarily audible indicators include U.S. Pat. No. 4,187,494, issued to John W. Jessee on Feb. 5, 1980, disclosing a vehicle alignment device having a tone generator simulating a human voice to deliver verbal instructions. The simulated instructions include the directions right and left.
Another example is U.S. Pat. No. 4,854,604, issued to Bradley E. Stallsworth on Aug. 8, 1989, disclosing a vehicle alignment device having an audible alarm. Stallsworth further states that the alarm could be visual, but provides no details.
The device of Roberts appears to offer more useful input to a driver than other prior art examples. However, direction and proximity are separately indicated, and it is extremely difficult for most drivers to take in at a glance the true respective positions of the two vehicles.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.